Wave receiving apparatus



Jan. 27, 1931-. P. E. M IVER 54 WAVE RECEIVING APPARATUS Filed April 6, 1928 Patented Jan; 27, 1931 marten stares" PERCIVAL nnwAn-n nerves, 'or auenteiinnnw znAL inn WAVE RECEIVING ArrARA'r s Application filed April e, 1928, Serial 1:5. eeaee'i, and in New zeaiand. may 25,1921

This invention relates to systems for eliminating the effects of interfer ng electric waves HPOIITBCQlVlIlg circuits in radlotelephony or telegraphy, and for like purposes in 5 wired telephony or telegraphy.

The object of the present invention is to provide a very etficient means of combating the effects of such interfering electric waves upon the receiving circuit-s. 7

At present, the methods employed for this purpose may be classed under two general headings V (1) The use of a series of tuned amplifier circuits arranged with valves in stages whereby the amplitude of the desired wave is gradually increased at each step, and that of undesired waves are gradually reduced.

' (2) The useof special trap or absorption circuits whereby the intensity of the inter-.

2c fering wave is greatly reduced.

Regarding (1), this 1s certainly a sure way of achieving theobject, provided, however, the number of stages 1s sufic1ent,'part1cularly when the source of interference is nearby or powerful, but which ultimately becomes 'unwieldly to operate in the selection of any wave. In v(f2) the arrangement is most ineflicient, particularly when the interference is powerful, inasmuch as to reduce in any satisfactory degree the intensity of such interference necessitates the absorption of a large amount of power from the circuit, and the absorption reduces seriously the intensity of the desired wave also, which is perhaps already very weak. Even when the arran ement is de- 's1gned to be of low loss, an th1s lmplies sharp tuning, the consequence of such sharp r tuning is that no care is taken of'side band' 40 frequenc1es inherently attendant upon carrier waves of the modulated type; consequently, the interfering wave breaks through in a very disconcerting manner. v v

My invention provides means for taking 4 care of the main carrier wave with its attendant side bands and also of possible small V tirely eliminated."

These results are obtained by first collect,-

eachother so that no currents ofthat wave, therefore, flow and influence the amplifier circuits handling the desired wave; c

In other words, by; taking a; small portion of the energy from an electric waveinthe aerial of a radio receiver andamplifying the interfering 0r 1 undesired) wave only: and using this potential to impress its characa teristics on another electriccircuit in the apparatus in a certain way, the interfering (or undesired) wave n the main'c1rcu1t is en- By tuning,the interfering ,waveonly is carried to the point inthe second circuit where the elimination takes place. a

The second circuit mentioned (wherethe elimination takes place): being aperiodic transmits both the desired ..and the. undesiredwaves as received by induction from the-inductance coil of the antenna acting in one-direction. Into this circuit is introduced .the opposing potential of the same wave length and intensity as the undesired wave,

thus neutralizing the undesired'fwave.

By referring to the accompanying diagram it will be seen that the aerial inductance A. is coupled toone turn C of a coupling or link transformer which is by one turn C coupled to amplifier inductance B, the ends of which lead to the receiver or amplifier- J of the desired wave. a y

Inserted between C, and C are another one or tWoturns- G which forms the point at whichthe'interfering waves are eliminated. To bring about this elimination, inductance D is loosely coupled to A and has induced therein small electromotive forces from A of the interfering 'wave'which being. ampli fied and tuned by the system comprising coil E, condenser F and battery G in the platecircuitof the amplifying valve H are impressed on C in a direction such that the electromotive forces-produced therein are exactly opposite in vphase but of-equal magni-. tude to those produced by the same-Wave at C. Under suchconditionsno current of t C, C C onlythat of the desired anclother' weak Waves, consequently, nomagnetic field of the interfering-wave influences B. Having thus eliminated the effects of interferences before the amplifying circuit J is reached it is now unnecessaryto useI-a mul- 'tiplici'ty 'oftuned'amplifier or filter circuits as 'before describedin method (1) above.

lvhatlclai n is:-" 1. In a system of thech-aracter, described,

an aerial circuit havingan inductance ele-,

m'ent,':a main circuit-inductance element, a coupling circuit including 'termi-nalcoilsand an' intermediate coil'f-the terminal coils h eing inductively related to the aerial andmain circuit inductive elements 'and meanscoupling the aerial inductance element andtheintermediate coil of said coupling circuit for impressing electromotive forces from an interfering Wave on the intermediate coil.

2. A device as claimed in claim 1,;characterized in thatsaid means includes an'inductance element in inductive relationtothe aerial inductance element,- a circuitconstituted in part by-the last.mentioned induc tance element, and tuning means in said circuit. r

3. A device as claimed in claim 1, characterlzed 1n that said means includes an 1nductance element in inductiverelation to:the

aerial inductance-element, a circuit constituted in part by the last mentioned inductance element, tuning means in said circuit, and amplifying means in said circuit. V r

In testimony'fwhe're'of, I'have signed my name to this specification. -i

PERCIVAL EDWARD MoI-VER.

116 interfering Wave canfiow round the circuit I 

